Portable displays or wearable displays worn by the user on the head such as head-mounted display (HMD) have been recently widespread, and many users are using these portable or wearable display devices during moving or exercising. However, these portable or wearable display devices vibrate with the movement of the user, and thus it is difficult to recognize information displayed on a display unit disadvantageously. The difficulty in recognizing such displayed information causes accidents due to distraction of attention to the surroundings and induction of eye fatigue, which may cause the occurrence of dangerous situations.
In particular, the display device displaying a video viewed by the user while being worn on the head, that is, the head-mounted display (HMD) is not necessary to be carried by the user, and the user can enjoy a favorite video or music while exercising such as walking or running. On the other hand, it is disadvantageously difficult to prevent vibration caused by the exercise such as walking or running, which lead to increased difficulty in recognizing information displayed on a display unit.
Moreover, the head-mounted display (HMD) has a display unit that is observable by the user with either one or both the eyes, and is configured to be able to control visual and auditory sensation in combination with a headphone. An example of the related art that has described the structure and principle of the head-mounted display includes Patent Literature 1 (JP 2011-145488A).
As described above, in using a portable or wearable display device, the displayed information can be recognized in a relatively stable state if the user is stationary. However, if the user performs an action such as walking or running, it is disadvantageously difficult for the user to recognize the display information.